Sunday, March 13, 2011

Perryville Trace Stormwater Control Gets a Severe Test

Since it was opened in 2008, the Perryville Trace has been subjected to flooding along about 50 yards of its length by stormwater from Brookside Avenue. The runoff has created a nearly level sandy plain in the woods between the Trace and the railroad. New runoff spreads out over this area and onto the Trace at several locations. Last spring, we located the lowest of those locations and placed pipe under the Trace to direct the outflow to the river. The rain and snowmelt of the week of March 6 put our handiwork to the test. What we found was that every stick on the flat plain quickly collected a glob of wet leaves, creating small dams which directed flow away from the most natural path to our pipes. The solution was to rake out the route we wanted the water to take and turn the dams into levees. This went a long way toward getting all the water to the pipe. Perhaps it means there will need to be a maintenance task performed every fall to clear the way. Stormwater flows from Brookside Avenue for days after the rain stops. Even if the pipes don't keep the Trace dry during the heaviest rain and snowmelt, they at least give it a chance to dry soon afterward by carrying away the continual flow.

Another challenge for the Trace has been the narrow causeway between the river and a pool that forms every winter. Typically this is flooded by one or both at some time during the spring. Last year, it became something of a quagmire. Trail users put small logs across it, which seemed as likely to break an ankle as to keep one's feet dry. Last year, students from Shepherd Hill High School built up the causeway and paved it with flat stones from the site. At this point, it appears the river would have to reach flood stage to get it wet, but an inch of water comes over it from the pool. However, the stones keep the surface stable, so it is much safer to traverse.

1 comment:

  1. How long did it take to rake out all of the debris? And how many people were involved?
    -Jackie @ Inlet Filters